Just write. Write about your day, your job, your family, your hobby, your imaginary alternate life. Just write. Your writing doesn't have to rhyme, doesn't have to make sense, doesn't have to have a story, doesn't have to be real, doesn't have to follow any rules. Just write.

Once you have written 10 pages of misc. thoughts and rambling prose, you will have at least a dozen ideas for new songs. Separate out the individual lines or parts of lines that really grabbed you or made you chuckle or made you think. You now have some specific starting points for your songs.

Use your imagination and try to come up with at least one verse or chorus using each of the separate ideas you came up with. By this time you will certainly have found at least one good start to a song. Take this beginning and work with it until it becomes the song you want it to be. Don't stop tweeking it until it sounds great.

I have used this technique to write songs when I've thought I was mentally blocked. It works for me, hope it works for you.

Best wishes,
Mike